x c conditioning of organic mgbfients



\ U TED STATES ancestry l l Patented FebgiS, 1945 oonnnrxomneoe ORGAN C jP Gfi- Marie ScalerafSomervillq m assign to Ame fican Gyanamid company; New York,

N 1, a-ocrporation of Maine y N0 Drawings Application a ass-1 94i j Serial No. 413367 t 13 Claims. mista en) This-inventionrrelates to a processloriniprovmg: the physical form or vat dyestufis-byian acid pasting methodr Many vat 'dyestufis are purified by the wsocalled,

acid-pasting method which involves-solution of the pigment in sulfuric acidnfollowed by precipi tation by an aqueous medium such as an excess,

of nwater or dilute suliuricmcid. This is comiiid'andlin general a wide variety of immiscible liquids may be used, some of which are soluble fiii's iliuric acid and some of whicharei not;

While the invention is not limited broadly to any monly known intheartasacidepastin-g; although strictly speaking the expression is a misnomer-as actual solution of the pigment in the sulfuric acidtakes place. ncid pasting has commonly been employed with any vathdyestuif soluble in sulfuric acid; Some vat dyes, such as anthri I is ofrelativelylo-Wsolidscontent. The l'owsolids content makes'it diifi'cult'ltopreparedyeing pastes water presentinkthe paste'results.

According tofhhe present invention it is found that the acid pasting procedure can begreatly improved by carrying out the dilution stepiin the of gre'ater strength as excessive dilution with the presence ofwa water-immiscible neutra'l organic liquid. In the casecf'most vat drestufrsthis rel-1 sults itr the production of a filtercakecf greatly increased solids content. a The increase in solids content 'ob'tainable by the present invention will vary with differentdyestufis and different solvents; but when the best solvent for anypartic ular dyestuff is used the increase is always'con siderable and; in every case imakes'ta commercially morezdesirable paste which: isnot subject to the disadvantage that large; amounts of water 7 l have to be shipped as in the pastes of .thepri'or art where thesolids content after aoid pa sting was uitelowL 1 a i The: process of the present invention should not be' -confused withrcertain processes in which sulfonated organic compounds have been used in acid pasting inthe form of wetting'agents which particular organic liquid,, difieren't liquids .give

varying results'with different pigments and in each case theoptimum should be chosen. Improved results are. generally obtained with any suitable organic liquids. Preferably the amount of organic liquid should be at least 20% of the weight of the pigment.

The present invention is not limited to the introdiiction oi the organic liquid at any particuf lar stage of the acidpasting; Thus for example, in the" case of; organicliquids which are soluble in concentrated sulfuric acid and' which arefinot sulfbjnated such as nitroben'zlen'e, e't'hers and the like, theyjmay be addedjto the sulfuric acid solu tion prior to dilution. Inthe; case of otherpr-f ganic liquids which are subject to sulionation it isflpi'eferablc to disperse the organicliquidwith the water or dilute sulfuric acid which is used to precipitate the pigment. Without-intending to limit thepre'sent invenicn, some timical o'r ganic liquids in addition .to nitrobenzene are the following: homologues of benzenegsucli as tolue ene. xylene, p-cymene', mesityle'ne, turpentine,

Solvesso #2 (a hydrogenatedpetroleum prod? uct of predominantlyarom'atic nature), mixed hexanes, esters such as amyl butyratal diethyl phthalate; ethers such as amyl 'benzyll ether di-ta yiethen. dibutylether, diphenyl ether, n-butyljphenyl ether; aliph atic halogen compoundsasuch as carbon tetrachloride and symmetrical tetra-b chloroethane-and the like. It; will be evidentithat all of' the above enumerateduliquids are neutral, i

that is, they willznot react" With either acidsor bases. Particularly with vat dyestuffs of the an:

areretainedin therpigment andincreasetits wet l inability, Sucn wetting agents are sulfonated alkylatednapht-halene, sulfonated dinaphthylmeth ane, and the like, and they are not water-immise cible organic liquids and hence do not perform the function of the present invention and such procedures arenotincluded. t i l a {The present-invention is not limited to any particular water-immiscible neutral organic liq- (C. I. 1095) Calcosol VioletBN ((3. 1.1163), Calthraquinone; series, hitrobenzeneappears to be preferable although good results are obtained with toluene, xylene, o-dichlortbenzene, and the like. i .Typical examples of the: pigments: which can be treated by the present invention ar nas iollows: various vat dyestuff of the anthraquinone series such as lAedibenzoyldiamino anthraquinone (0. I. 1i31 qCalcosol Olive R (CJI. 1150),

Calcosol BrownR (C. I. 1 15,1) Calcosol Blue RS (c-Iw L106), Galcosol Blue GCD (C, I. 1113) ,and

other halogenated indanthiienes; Caloosol Yel' low: a ea. 1.: 1-118) ,"Pyranthrone (o. I. 1096) an its halogen; derivatives such as CalcosolxFlamin'g Orange 2R (C. I. 1093) and Calcosol GoldenOr ange RRTT (Ct-I. 1097i), Ca -lcosol Yellow'GC PATENT OFF CE zole ring systems through dehydrogenation.

Thus, when 4,4 dibenzoyldiamino 1,1 dianthrimide is dissolved in sulfuric acid the positions 3 and 3 are connected to form a carbazole nucleus and the above-mentioned Calcosol Olive R results. The same happens to the 4,5'-dibenzoyldiamino-1,1'-dianthrimide which gives the above mentioned Calcosol Brown R. In cases like this it is possible to dissolve the dianthrimide in sulfuric acid and after the ring closure hasbeen accomplished to dilute the solution with water in the presence of a water non-miscible organic liquid Without previously isolating the desired vat dyestuff. The organic liquid may be added before orafter. the ring closure. The concentration of the sulfuric acid will vary with the type of dyestuif used. While in the great majority of cases a concentration of over 90% is used, there are a few cases where a lower concentration is better. Thus, the 4,4'-dibenzoyldiamino anthraquinone hydrolyzes too easily in more concentrated sulfuric acid and it is therefore advantageous to use an 85% sulfuric acid in this case. v The amounts of water to be used in the precipitation will also depend upon the individual dyestuffs and will furthermore depend on whether it is desired to perform a purification at the same time as it is e. g. customary with the indanthrenes and it will further depend on whether it is desired to precipitate the dyestuff or pigment as. such or as the sulfate. In the latter case it is sometimes advantageous to dilute not with water, but with dilute sulfuric acid.

The invention will be described in greater detail in conjunction with the following examples but it is not limited to the details thereof. The parts are by weight.

Example 1 One part of the carbazole corresponding to 4,5'-dibenzoyldiamino-1,1-dianthrimide was dissolved at room temperature in 10 parts of 68 B. sulfuric acid and 1 part of nitrobenzene. The solution was drowned in 100 parts of water under stirring. The precipitated dyestufi was filtered and washed, neutral. The wet filter cake was freed from nitrobenzene by means of steam and filtered again. I The resulting presscake contained 37% solids. A similar experiment conducted without nitrobenzene gave a presscake of only 21% solid content; prolonged boiling of the latter presscake in aqueous-suspension, filtering and pressing gave an increase to only 22% solid content.

Example 2 One part of the same dyestuff (used in Example 1) was dissolved in 10 parts of 66 B. sulfuric acid. The resulting cherry red solution was drowned in a. well agitated emulsion of 1 part of nitrobenzene in 100 parts of water. The precipitatewas filtered, washed, then freed of nitrobenzene by steam, filtered again.

The resulting filter cake had a solid content of 38%. When toluene was used instead of nitrobenzene, the final press cake contained 33% solids, with xylene 31%, with o-dichlorobenzene 32%. To obtain these effects the organic liquid must be finely dispersed in the precipitating water, 1. e. good stirring is essential.

Example 3 One part of the carbazole corresponding to 5,5'-dibenzoy1diamino-1,1-dianthrimide was dissolved in 10 parts of concentrated sulfuric acid, the solution was drowned in a well stirred emulsion of lpart nitrobenzene in 100 parts of water. The filter cake was treated as described in Example 2. a

It contains 38% of solids. A filter cake of this dyestufi prepared in the absence of nitrobenzene contained only 14.7% solids.

Example 4 One part of 2,8-diphenyl-anthracene 265) dithiazole'-6,12-dione was dissolved in 10 parts of concentrated sulfuric acid. The clear solution was drowned in a well agitated emulsion of 1 part .nitrobenzene and 100 parts of water, the nitrobenzene was removed with steam, the yellow slurry was filtered and washed.

A presscake resulted containing 43% solid dye as compared to a 22% cake obtained in a normal acid-pasting without nitrobenzene.

Example 5 Example '6 One part of 4,5 dibenzoyldiamino 1,1-dianthrimide was dissolved in 10 parts of 66 B.

sulfuric acid containing 1 part of nitrobenzene. After agitating at room temperature for three hours to effect the ring closure to the carbazole the resulting solution was drowned in 100 parts of water. To this slurry was added 1 part of sodium dichromate and stirring was continued for three hours at 35. The precipitate was filtered and washed, freed from nitrobenzene by steam and filtered again.

A press 1 cake resulted of 31% solids content, compared to a presscake only 18% in solids when no nitrobenzene was used. Using 0.5 part of nitrobenzene per part of dianthrimide resulted in a'press cake of 24% solids; using 0.25 part gave a presscake containing 22% of real dyestuff.

Example 7 One part of 4,4 dibenzoyldiamino .1,1' dianthrimide and 0.5 parts of nitrobenzene were dissolved in 10 parts of 66 B. sulfuric acid.

Example 8 Two parts of 4,4-dibenzoyldianfinoanthraquinone and 1 part of nitrobenzene were dissolved in30 parts of 85% sulfuric acid. The resulting solution was drowned in 250 partsof water, the

precipitate filtered and washed. The cake was, freed from nitrobenzene by steam distillation and filtered again.

The resulting presscake contained.42.6% dyestuff while the presscake obtained by an ordi- A nary acid-pasting contained only 16% of solids.

Example 9 To 195 parts of 98% ricsoi), wereadded in parts of symmetrical tetrachloroethane. The} chloro compound did not dissolve in the acid I even after stirring. The mixture was then cooled to 15-20 and, with stirring, 25 parts of 4,4'-dibenzamido-1,1'-dianthrimid slowly added. I The temperature was kept below 20 by external cool ing. After all the dianthrimid had been added,

dye was filtered (unwashed neutral, and stripped for one hour, again filtered and pressed dry. The resulting presscake had a solids content of 32%,

as compared to 20-25%, solids when prepared without the organic solvent. s

I claim: l

1. A process of producing presscakes of vat pigments having an enhanced solids content which comprises dissolving the pigment in strong sulfuric acid, diluting the same with an aqueous i i 3 ence of an amount of water-immiscible neutral organic liquid at least 20% the weight of the pigment, and removing the liquid by physical means.

3. A process of preparing a carbazole pigment in the form of a presscake having an enhanced solids content which comprises dissolving an u,u'- 1 dibenzoyl diamino-1,1-dianthrimide in conceni trated sulfuric acid and precipitating by dilution with an aqueous medium in the presence of a water-immiscible neutral organic liquid at least 20% of the weight of the pigment, and removing the liquid by physical means. i i 4. A process of preparing a carbazole pigment in the form of a presscake having an enhanced solids content which comprises dissolving an mac'- dibenzoyl diamino 1,1'-dianthrimide in concentrated sulfuric acid precipitatingby dilution with an aqueous medium in the presence of an amount of a water-immiscible neutral organic liquid at least 20% of the weight of the pigment, andremoving the liquid by physical means. i i a 5. A process according to claim 1 in which the organic liquid is nitrobenzene.

. organic liquid is nitrobenzene.

organic liquid is nitrobenzene.

immiscible neutral organic liquid at least 20% the weightof the pigment, and removing the liquid by physical means.

2. A process of producingpresscakes of vat 5 distillation.

6. A process according to claim 2 in which the organic liquid is nitrobenzene.

'7. A process according to claim 3 in which the 8. A process according to claim 4 in which the 9. A process according to claim 1 in organic liquid is xylene. h

1 A process according to claim 2 inwhich the organic liquid is xylene.

organic liquid is xylene.

l2. A process according to claim 4 in which the organic liquid is xylene. i medium in the presence of an amount of water- U .13; A process of producing presscakes dyestuffs having an enhanced solids content which comprises dissolving'thepigment in strong sulfuric acid, diluting the same with an aqueous medium in the presence of a water-immiscible neutral organic liquid at least 20% of the weight of the pigment, and removing the liquid by steam MARIO scALERA.

which the J 

